Anvimo 480mg Tablet is used to prevent CMV infection and disease in CMV-seropositive recipients of an allogeneic HSCT.

Letermovir prophylaxis is generally started after transplantation, according to the transplant team's treatment plan. In adults receiving HSCT, prophylaxis is generally continued through 100 days after transplantation. Some patients at risk of late CMV reactivation may require prophylaxis for longer.

Letermovir is also approved in some settings for prevention of CMV disease in high-risk kidney transplant recipients. However, the appropriate indication and dosing depend on the patient's transplant status, CMV serology and local prescribing guidance.

Letermovir blocks the CMV DNA terminase complex, which includes the viral proteins pUL51, pUL56 and pUL89. This complex is required for processing and packaging CMV DNA into mature virus particles.

By interfering with viral DNA processing and packaging, letermovir prevents the formation of mature CMV virions and helps reduce the risk of CMV infection and disease after transplantation.

Letermovir can cause clinically important interactions because it affects several drug-metabolising enzymes and transport proteins. It may also be affected by medicines that alter these pathways.

• Cyclosporine: The letermovir dose is reduced to 240mg once daily when used with cyclosporine in adults and appropriate paediatric patients.

• Tacrolimus: Letermovir can increase tacrolimus concentrations. Close therapeutic drug monitoring and dose adjustment may be required.

• Sirolimus: Blood concentrations may increase and monitoring is recommended.

• Certain statins: Letermovir can increase concentrations of some statins. Particular caution is required with simvastatin and pitavastatin when cyclosporine is also being used.

• Pimozide and ergot alkaloids: These combinations are contraindicated because letermovir can increase their concentrations and cause serious adverse effects.

• Certain anticonvulsants and other enzyme inducers: Medicines such as phenytoin and carbamazepine may reduce letermovir exposure and its effectiveness.

• Rifampicin and St John's wort: These can reduce letermovir concentrations and are not recommended with letermovir.

• Some CYP3A substrates: Letermovir may increase their concentrations, so dose adjustment or monitoring may be required.

Tell your doctor about all prescription medicines, over-the-counter medicines, vitamins and herbal supplements you take before starting treatment.

• Store Anvimo 480mg Tablet in the original package until use.

• Keep the tablets protected from moisture.

• Store the medicine according to the temperature conditions stated on the product packaging.

• Keep it out of the reach of children.

• Do not use the tablets after the expiry date.

Take Anvimo 480mg Tablet exactly as prescribed by your doctor.

For adults receiving an allogeneic HSCT, the usual dose is 480mg once daily. When used with cyclosporine, the dose is generally reduced to 240mg once daily.

The tablet can be taken with or without food. Swallow it whole with water. Do not crush, chew or split the tablet unless your doctor specifically advises you to do so.

Treatment should be continued for the duration prescribed by the transplant specialist. Do not stop treatment on your own, even if you feel well, as the medicine is being used to prevent CMV reactivation or disease.

If you miss a dose

Take the missed dose when you remember. If it is nearly time for your next dose, skip the missed dose and continue with your regular schedule. Do not take two doses at the same time to make up for a missed dose.

The commonly reported side effects of letermovir include:

• Nausea

• Diarrhoea

• Vomiting

• Peripheral oedema

• Cough

• Headache

• Fatigue

• Abdominal pain

Tell your doctor if side effects are persistent or troublesome. Seek medical attention if you develop severe or unusual symptoms during treatment.

• Take the medicine at the same time each day to maintain consistent antiviral coverage.

• Let your transplant team know about every medicine or supplement you take because letermovir has several clinically important interactions.

• If you are taking cyclosporine, your letermovir dose will usually need to be reduced.

• Tacrolimus, sirolimus and other immunosuppressants may require closer blood-level monitoring during treatment.

• Do not use letermovir to treat an established CMV infection unless specifically directed as part of a treatment plan. It is primarily used for CMV prophylaxis.

• Continue the prescribed course even if you have no symptoms, as CMV can reactivate without obvious symptoms in transplant recipients.

• CMV monitoring may still be required after prophylaxis, particularly following HSCT.

• Do not change the dose or stop treatment without speaking to your transplant specialist.